---
cve: "CVE-2026-63495"
severity: "HIGH"
cvss: 7.5
epss: "0.5%"
vendor: "libevent"
kev: false
exploited: false
published: "2026-08-20 18:16:37"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-27T22:05:21+02:00"
---

# CVE-2026-63495

> 7.5 HIGH · 🧪 PoC

## Beschreibung

Libevent is an event notification library. From 2.2.0-alpha-dev until 2.2.2-alpha, the libevent WebSocket server in ws.c accumulates fragmented frames in evws->incomplete_frames without enforcing a total message-size limit. An unauthenticated remote client can repeatedly send fragmented WebSocket frames below WS_MAX_RECV_FRAME_SZ with FIN=0, causing the evbuffer to grow without bound until the process or host exhausts memory. This issue is fixed in version 2.2.2-alpha.

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **poc**
  - Automatable: **yes**
  - Technical Impact: **partial**

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- 291c4d1cd75695e898030ebd5c4ddf26c094077b (Commit)
- df3ecad3a040fd6d4fad4287defe113395de6fd7 (Commit)

## Referenzen

- <https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx>
- <https://github.com/libevent/libevent/commit/291c4d1cd75695e898030ebd5c4ddf26c094077b>
- <https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-63495) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_